So, what is genetic testing and why is it needed?
Through scientific studies, it has been found that Golden Retrievers have seven common genetic deficiencies (described below). These genetic deficiencies can be passed from parent to offspring through their DNA. A strand of Golden Retriever DNA is very similar to human DNA, as there are two genes that make up a strand of DNA. One (1) gene from each parent is passed to their offspring. The pairing of these genes will decide the make up of a puppy's DNA.
Genetic deficiencies fall into three categories: clear, carrier and affected. To be "clear," both genes must be considered good. To be a "carrier," one gene is good and the other is bad. But don't be thrown off by the word "bad." Having one bad gene is not a bad thing. Your puppy/dog will never show signs or symptoms of that deficiency. They can only "carry" that deficiency (in their DNA) and potentially pass it along if they ever had puppies of their own. To be "affected," both genes are bad. It is never a good thing to breed two affected parents as their offspring will be always be affected. Please, stay away from a breeder who feels testing is not important. It is very important. Each genetic deficiency has been scientifically identified for a reason. As a breeder, our job is to better the breed, not produce bad puppies just for a quick dime. This is why we put a lot of time, energy and money into having our dogs/puppies tested.
The color coded chart below shows how pairing parents with different DNA (clear, carrier or affected) will affect the type of puppies they'll produce. A puppy can be considered "cleared by parentage" only if both parents are "clear." Please note, the percentage is only the average and can flex one way or another.
NTX Goldens genetically test each puppy through Animal Genetics for the seven common genetic deficiencies found in Golden Retrievers, unless cleared by parentage. We are proud to say, none of our puppies (or our adult breeding Retrievers) are affected by any of these genetic deficiencies. We carefully select our dams and sires to achieve this standard. Genetic Testing results of our litters and breeding Retrievers can be found on their respective page. You'll receive a copy of genetic testing results (of both parents and puppy) should you purchase a puppy from NTX Goldens. We do not hide any of our results (good, bad or ugly). You'll see on our adult page that we list every test result. If a breeder does not list all seven deficiency testing results, throw up the red flag and ask why. Demand to see all results. Most breeders will only list the good results or use wording that can be misconstrued. Ask specifically if they are "clear," "carriers," or "affected."
Below is a brief description of each of the seven common genetic deficiencies found in Golden Retrievers.
Progressive Retinal Atrophy (PRA-prcd)
Progressive Rod-Cone Degeneration (prcd) is a form of Progressive Retinal Atrophy (PRA) in which the cells in the dog's retina degenerate and die. PRA for dogs is similar to retinitis pigmentosa in humans. Most affected dogs will not show signs of vision loss until 3-5 years of age. Complete blindness can occur in older dogs. prcd is a form of PRA known to affect over 40 different breeds.
The retina is a membrane located in the back of the eye that contains two types of photoreceptor cells. These cells take light coming into the eyes and relay it back to the brain as electrical impulses. These impulses are interpreted by the brain to "create" images. In dogs suffering from PRA-prcd, the photoreceptors begin to degenerate, causing an inability to interpret changes in light. This results in a loss of vision. Rod cells, which normally function in low-light or nighttime conditions, begin to degenerate first. This leads to night-blindness. The cone cells, which normally function in bright-light or daytime conditions, will deteriorate next. This often leads to complete blindness over a period of time.
Ichthyosis-A (ICH-A) is an autosomal recessive genetic mutation that affects the skin of Golden Retrievers. The mutation prevents the outer layer of the epidermis from forming properly, resulting in skin that becomes darkened and thick, with excessive flaking.
The name "Ichthyosis" is derived from the Greek word for fish. This describes the skin's resemblance to fish scales. The most common symptom of ICH-A is excessive flaking of the skin. Other symptoms include areas of hardened skin and hyperpigmentation, which may make the skin appear dirty or blackened. Symptoms can be mild or severe. Evidence of the disease may be detected when the dog is still a puppy, but symptoms may take a year or more to develop. Additionally, symptoms can improve or worsen, depending on stress and hormonal cycles.
ICH-A is generally not dangerous to a dog's health but can be unsightly and uncomfortable for the dog. ICH-A is frequently related to other health issues such as yeast overgrowth and fungal infections. A dog diagnosed with ICH-A will usually require more care with special shampoos and treatments. ICH-A is unfortunately quite common in Golden Retrievers but can be identified with a simple DNA test. A dog with ICH-A would need to inherit the mutation from both parents, as the mutation is autosomal recessive.
Degenerative Myelopathy (DM)
Degenerative Myelopathy (DM) is a progressive neurological disorder that affects the spinal cord of dogs. Dogs that have inherited two defective copies will experience a breakdown of the cells responsible for sending and receiving signals from the brain, resulting in neurological symptoms.
The disease often begins with an unsteady gait, and the dog may wobble when they attempt to walk. As the disease progresses, the dog's hind legs will weaken and eventually the dog will be unable to walk at all. DM moves up the body, so if the disease is allowed to progress, the dog will eventually be unable to hold his bladder and will lose normal function in its front legs. Fortunately, there is no direct pain associated with DM.
The onset of DM generally occurs later in life starting at an average age of about 10 years. However, some dogs may begin experiencing symptoms much earlier. A percentage of dogs that have inherited two copies of the mutation will not experience symptoms at all. Thus, this disease is not completely penetrant, meaning that while a dog with the mutation is likely to develop DM, the disease does not affect every dog that has the genotype.
Progressive Retinal Atrophy (PRA) GR-PRA1 & GR-PRA2
Progressive Retinal Atrophy (PRA) is a category of genetic mutations that cause vision loss and blindness. Photoreceptor cells in the retina begin to degenerate, typically progressing from a loss of night vision to complete blindness. PRA affects many different dog breeds, and these mutations are breed-specific. In Golden Retrievers, two mutations have been identified in addition to prcd-PRA known as GR-PRA1 and GR-PRA2.
Both GR-PRA1 and GR-PRA2 are inherited in an autosomal recessive manner. This means that a dog must inherit a copy of the mutation from each parent to be affected by the disorder. Dogs with one copy of the mutation will not show any signs or symptoms of PRA, however, they can still pass on that mutation to any offspring.
Muscular Dystrophy (MD)
Muscular Dystrophy (MD) is a mutation of the dystrophin gene that causes a deficiency of dystrophin proteins in Golden Retrievers. The lack of dystrophin proteins leads to the progressive degeneration of skeletal and cardiac muscles. The disease is similar to the human disease, muscular dystrophy. Symptoms appear relatively quickly, at about six weeks to two months of age. A dog with muscular dystrophy will exhibit muscle weakness, difficulty standing or walking normally, and difficulty swallowing. Symptoms can range from relatively mild to severe, but MD is generally fatal at about 6 months of age.
The MD mutation is sex-linked and located on the X chromosome. So, while both male and female dogs can be affected, MD is mostly a disease related to male Goldens. Females can be carriers of the mutation, however, will not exhibit any symptoms.
Neuronal Ceroid Lipofuscinosis (NCL)
Neuronal Ceroid Lipofuscinosis (NCL) is a progressive degeneration disease of the central nervous system. In Golden Retrievers, NCL is caused by a 2 base pair deletion in the CLN5 gene causing a frameshift and premature termination codon.
Affected Golden Retrievers begin to develop signs of the disease around 13 months old. Often the first sign of NCL is a loss of coordination during basic movements including walking, running, climbing stairs, particularly when excited. As the disease progresses, the loss of coordination becomes evident even when the dogs are calm; the dogs may also experience tremors, seizures, or blindness. Compulsive behaviors, anxiety, and loss of previously learned behavior are also common. Affected dogs may likewise become agitated or aggressive as the disease continues to progress. Due to the severity of the disease and loss of quality of life, most affected dogs are euthanized by 2-3 years of age.